Compared with an tranditional liquid electrolytic capacitor, a solid electrolytic capacitor has advantages such as prominent electrical performance, a low equivalent series resistance (ESR), a highly ripple-tolerant current, a long life, and stable performance. Continual upgrading of electronic products brings higher functionality and performance and also imposes higher requirements on high-frequency characteristics of the capacitor. People reduce the ESR of the solid electrolytic capacitor by different means to satisfy the high-frequency characteristics of the capacitor.
However, although the solid capacitor has its irreplaceable advantages, the current state of the art has two main problems. One problem is that the voltage of a product cannot be too high and could not be as high as 35V, and the other problem is that the leakage current of the product is high enough to exceed 0.05 CV. Reasons for such problems are: During the process of manufacturing a solid capacitor, monomers and oxidants are generally dissolved by using a solvent, and enter a capacitor core by means of impregnating, and then are polymerized under specific conditions to generate a conductive solid electrolyte. This manufacturing process has two disadvantages. One disadvantage is that the oxidant itself is highly acidic and strongly damages the oxidiation film of the positive electrode foil, thereby significantly reducing the original voltage value of the positive electrode foil. The other disadvantage is that the monomers and the oxidant are dissolved in the solvent and infiltrate the capacitor core, and as the positive electrode foil is well impregnated in the solvent, the oxidant and the monomers are brought into etched pores of the anodized foil. The pores, where the oxide film is generated in the chemical treatment process, are fragile, plus the solid electrolyte is not repairable, hence, the withstand voltage of the pores is low. When a specific voltage is applied, a high leakage current is generated and leads to failure of the product.
A technical solution to this problem is to polymerize a conductive polymer in water to form a water dispersion, and then the conductive polymer infiltrates the capacitor core by impregnating. A capacitor formed in this way prevents the oxidant from impairing the foil, so that the withstand voltage of the product is higher. In addition, molecules of the polymer dispersed in the water have a specific size. Because the polymer is dispersed in the water and the water generally provides a lower impregnation effect than the solvent, it is ensured that the conductive polymer infiltrates the pores of the positive electrode foil. Due to the presence of polymers, the fragile pores with a low withstand voltage prevent substantial electric leakage, so that the withstand voltage of the product is much higher.
In the current state-of-the-art, because an ordinary impregnation manner is applied without considering the low impregnation effect of water, the capacitance withdrawing rate of the product is low, it is difficult to make a product of a larger size, for example, larger than Φ10*12 mm, or product consistency is low.